Introduction

Tuberculosis (TB) is a contagious disease that has been around for a century and has caused significant public health concerns, mortality, and financial burdens over the past two decades. Mycobacterium tuberculosis infection results in active tuberculosis cases, with transmission occurring via coughs and sneezes.(1) However, TB prevalence has increased over the subsequent years, reaching 10.7 million active cases globally, with Southeast Asia accounting for the largest share of the global disease burden (34.00%). According to the Global TB Report (2025), the disease burden in developing countries such as India has worsened over the last two decades, accounting for 25.00% of global TB prevalence.(2) Based on the site of infection, TB is broadly classified into pulmonary TB (PTB), which primarily affects the lungs, and extrapulmonary TB (ETB), which involves organs other than the lungs, such as the lymph nodes, pleura, bones and joints, genitourinary tract, brain, pericardium, larynx, and abdomen.(3,4) The overall prevalence of TB from 2002 to 2024 showed that PTB cases in India increased from approximately 0.40 million to 1.76 million, representing a nearly 3.4-fold rise, and while EPTB cases increased more dramatically, from about 0.12 million to 0.64 million, corresponding to a 4.3-fold increase. During the COVID-19 period,(5–9) there was a significant decrease in reported TB cases, with PTB decreasing by about15.00–20.00% and EPTB by about 10.00–15.00% (Figure 1), which could be attributed to disruptions in healthcare services and delays in diagnosis.(10,11) India has witnessed a 21.00% reduction in TB cases between 2015 and 2024, decreasing from 237 per lakh to 187. This figure nearly doubles the global average decline of 12.00%, demonstrating that India is making significant progress towards achieving the Sustainable Development Goal (SDG 3) of eradicating the TB epidemic by 2030.(12)

The major comorbidities associated with TB are undernutrition, diabetes mellitus, smoking, alcohol use disorders, and HIV.(3,13,14) Undernutrition is a condition caused by inadequate food intake or poor nutrient absorption, which is required to meet the daily physiological requirements fora better health condition. It is considered to be the major risk factor, accounting for more than 40.00 to 50.00% of all TB cases each year in India.(13,15,16) Despite having relatively improved healthcare infrastructure and facilities, promising economic growth, food security, and strong policies, India still accounts for nearly one-quarter of the global undernourished population.(12,14) A recent nation-wide survey found that 18.70% of women and 16.20% of men suffer from chronic energy deficiency (BMI<18.5 kg/m²).(17) The prevalence of undernutrition was found to be more serious for pregnant women and children.(18) Similarly, 7.70% of children under 5 years reported severe acute malnutrition, while the prevalence of wasting exceeded 20.00% in several Indian states, including Bihar and Gujarat.(17) Insufficient energy intake and deficiencies in essential micronutrients such as iron, zinc, selenium, vitamin A, and vitamin D impair immunological function and increase the susceptibility to M. tuberculosis infections.(14,19) The relationship between undernutrition and TB is distinctly bidirectional, with undernutrition compromising host immune defences and facilitating progression from latent to active TB, and active TB further exacerbating undernutrition through increased metabolic demands, appetite suppression, muscle wasting, and micronutrient depletion.(15,16,20,21) This two-way interaction creates a never-ending cycle, with disease and nutritional deficiencies reinforcing each other, resulting in the "double burden" of TB and undernutrition.(20,21)

Figure 1: Prevalence of Pulmonary and Extrapulmonary TB cases in India (Source: WHO Database 2002-24)

This bidirectional relationship between TB and undernutrition has significant implications for treatment outcomes and TB elimination in India.(4,13,15) Individuals with undernutrition and active TB are more likely to experience delayed sputum conversion, unsatisfactory weight gain, treatment failure, relapse, and increased mortality, even with correct administration of anti-tubercular therapies.(15,22,23) Additionally, treatment failure increased the susceptibility to drug-resistant TB (DR-TB).(4,23) Poor nutritional status or protein-energy deficiency suppresses the immunity and changes Th1 cytokines and phagocytic function, limiting drug absorption and interfering with immunological recovery, further reducing treatment effectiveness.(19,23)At the community level, delayed recovery, persistent treatment challenges, and prolonged TB infections enable carriers to increase the infection within nutritionally vulnerable and healthcare-limited settings, thereby exacerbating the TB epidemic.(15,20,22) The prevalence of widespread undernutrition hinders the efficacy of biomedical control efforts and poses a significant challenge to achieving both national and global TB elimination and intervention strategies in India.(11,24) Without tracking nutritional deprivation or the magnitude of undernutrition alongside prompt diagnosis and treatment, progression toward TB elimination is likely to remain slow and unequal.(25,26) These considerations emphasise the significance of developing integrated, effective, and more robust nutrition-sensitive TB control methods, as well as synthesising existing biological, clinical, and programmatic knowledge on TB and undernutrition in an Indian context. This Systematic review synthesises biological, clinical, and policy-related information to investigate the bidirectional relationship between TB and undernutrition and the consequences for treatment outcomes and TB elimination efforts in India. The efforts will be made by utilizing the thematic-based approach to understand how TB and undernutrition are interconnected, including their biological causes, health impacts, and programme linkages in India.

Methodology

This Systematic review is based on the bidirectional relationship between TB and undernutrition in the Indian context. A literature search was carried out across multiple electronic databases, including PubMed, Scopus, Web of Science, ScienceDirect, and Google Scholar, to retrieve pertinent studies published from January 2015 to September 2025 (Figure 2). The search strategy combined keywords and medical subject headings related to tuberculosis, undernutrition, nutritional supplementation, treatment outcomes, and India, using appropriate Boolean operators (e.g., “tuberculosis AND undernutrition", “tuberculosis AND undernutrition AND India", "double burden of tuberculosis", “biological pathways of tuberculosis", and “TB elimination policy”). The search results identified a total of n = 216 published full-length articles and reports that include systematic reviews, meta-analyses, observational studies, clinical trials, and relevant national and international reports for inclusion. Grey literature and policy documents from authoritative sources such as the World Health Organization, the National Tuberculosis Elimination Programme (NTEP), the Ministry of Health and Family Welfare, and the National Family Health Survey were reviewed to get programmatic and policy perspectives. Following a comprehensive literature review and the application of the specified inclusion and exclusion criteria as depicted in Figure 2. A total of 63 manuscripts were retrieved to enhance the current understanding of this Systematic review work. The present research manuscript employed a Systematic review with a qualitative thematic approach to examine and connect the epidemiological patterns, biological mechanisms, clinical consequences, nutritional interventions, and policy responses related to the double burden of TB and undernutrition in India.

Figure 2: Flow chart presenting the selection process of the research studies on tuberculosis and undernutrition in India

Undernutrition as Fuel for TB Epidemic

Undernutrition remains a major comorbidity of TB in India, with evidence reporting a strong inverse association between Body Mass Index (BMI) and TB incidence. This bidirectional relationship indicates that individuals with low BMI or undernutrition (BMI<18.50 kg/m²), insufficient energy intake, and micronutrient deficiencies have compromised immunity and an increased risk of the latent to active stage of TB, indicating TB worsening the nutritional status or undernutrition through altered metabolism and nutrient malabsorption.(13,15,16,27) The persistent issue of undernutrition is exacerbating, leading to increased cases of drug-resistant TB (DR-TB), especially among individuals living in the same households and those who are already nutritionally vulnerable due to insufficient food or essential nutrients.(15,24) Recent national reports showed that a majority of adults with TB experience a substantial deficiency in energy intake, with this issue particularly prevalent in female individuals. The continuous upward trends and disproportionately high prevalence indicate that undernutrition may be the most persistent cause among TB patients in India (Figure 3). This situation frequently results in the co-occurrence of undernutrition and TB, especially among people who belong to economically disadvantaged or less privileged segments of society.(15,20) Studies consistently indicate that elevated prevalence of undernutrition is prevalent among individuals in lower wealth quintiles, those with limited educational attainment, and populations living in overcrowded, poorly ventilated environments characterised by inadequate sanitation and infrastructure.(28,29) These determinant factors contribute to delayed diagnosis, poor nutritional reserves at disease onset, and increased vulnerability to twofold adverse outcomes.(4)

Figure 3: Comorbidities associated with TB cases in India (India TB report 2022-24)

The concurrent high prevalence of TB and severe undernutrition, together with the double burden phenomenon, has significantly affected the tribal community in India.(30,31) The observational studies conducted across a few regions of India revealed that over 50.00% of TB cases among tribal populations are attributed to undernourishment.(13) This data includes findings from the Melghat tribes in Maharashtra,(32) the Saharia tribes in Madhya Pradesh,(33) and tribal communities in Manipur.(31) Additionally, gender dynamics play an important role in TB epidemiology, with males consistently accounting for a higher proportion of TB incidence and relapses, particularly during the period 2014–2024, likely reflecting differences in occupational exposure, health-seeking behaviour, and coexisting risk factors, such as the consumption of psychoactive substances (Figure 4). In 2014, there were around 1.05 million males against 0.55 million females, which represents close to two-thirds of the total TB burden. Over the last couple of years, the total TB burden in India has increased, with males accounting for roughly 60.00-62.00% of this burden. The percentage decreased from 66.00% in 2014 to approximately 60.00-62.00% in subsequent years (2024; 1.50 million males, 0.99 million females). From 2014 to 2019, the total prevalence increased almost steadily for both genders. Thereafter, a sharp decline was observed in 2020 due to COVID-19, followed by a strong rebound and steady rise after that was noticed. Likewise for both men and women, the total TB count was significantly affected by the pandemic and lockdown due to COVID-19 in the year 2020, followed by a recovery post-2020 and growth (Figure 4). Even though many patients' nutrition tends to get better during and after TB treatment, a significant number still face ongoing issues like low energy, muscle loss, and less body adiposity, showing a clear connection between TB and undernutrition.(23,30,31,34)

Figure 4: Gender-Based New and Relapsed Cases of Tuberculosis in India

Biological Mechanism of Double Burden

Active TB profoundly alters host metabolism and appetite, causing nutrient malabsorption and creating hypermetabolic conditions that contribute to progressive nutritional status decline, weight loss, wasting of lean muscle mass, and micronutrient deficiency. Morever, TB is characterized by an anabolic block in protein metabolism, in which dietary proteins are preferentially oxidized to meet elevated energy demands rather than used for tissue repair or immune function. The anabolic block is likely to contribute to the wasting observed in TB by limiting the ability to build or maintain lean muscle mass despite nutrient intake.(34,35) These metabolic alterations contribute to protein deficiency, muscle wasting, delayed recovery, and impaired immune responses, thereby worsening disease progression and compromising treatment outcomes in tuberculosis patients.(19,34,36) This imbalance often continues even when patients improve their dietary consumption, suggesting that inflammation interferes with muscle building and contributes to muscle reduction in tuberculosis patients.(19) Chronic inflammation and persistent immunological activity increase the basic energy requirements, leading to a state of hypermetabolism, followed by a loss of appetite and problems with absorbing nutrients and energy.(37–39) Pro-inflammatory cytokines, including tumour necrosis factor-α and interleukin-1, inhibit appetite and exacerbate nutritional decline, intensifying energy deficits and forcing the mobilisation of muscular and adipose tissues to meet metabolic demands. Simultaneously, active TB causes long-term oxidative stress by producing excessive reactive oxygen species during immune responses. This damages cells and makes metabolism even less efficient.(37,40) Evidence from Indian studies demonstrates reduced antioxidant capacity and increased lipid peroxidation among TB patients compared with healthy controls, particularly among those with pre-existing undernutrition.(37,39) Recent metabolic analyses also indicate impaired oxidative phosphorylation, enhanced glycolysis, and downregulation of tricarboxylic acid cycle intermediates, collectively reducing energy efficiency and amplifying caloric deficits.(37,41) Figure 5 illustrates that the convergence of chronic inflammation, oxidative stress, and energy deprivation results in TB-associated cachexia, a complex metabolic syndrome marked by rapid muscle mass depletion, weight reduction, and significant nutritional deterioration.(34,37) Moreover, TB associated with cachexia significantly reduces the quality of life and increases morbidity and mortality, which emphasizes the importance of integrated therapeutic strategies.

Protein-energy malnutrition (PEM) can induce a nutritionally acquired immunodeficiency that significantly impairs cell-mediated immune responses crucial for controlling M. tuberculosis infection (Figure 5), thereby increasing the risk of progression from latent infection to active disease and leading to poorer clinical outcomes. (15,21,38) The PEM is associated with thymic and peripheral lymphoid atrophy, lymphopenia, and reduced T-cell proliferation, resulting in a diminished pool of functional T lymphocytes critical for antimycobacterial defense.(21,38) Functional impairment of T cells leads to reduced Th1 cytokine production, including interferon-γ and interleukin-2, along with a relative shift toward increased Th2 cytokines, a shift away from effective immune response pathways necessary for clearing M. tuberculosis infections.(38,41,42) Further, PEM disrupts phagocyte activation by impairing signalling between interferon-γ and tumour necrosis factor-α. This disturbance in signalling compromises granuloma formation and increases within the host the ability to multiply M. tuberculosis.(38,42) Finally, the impaired antigen presentation disrupts the activity of phagocytosis and weakens the targeted immune response, collectively increasing susceptibility to active TB (38,42)

Micronutrient Deficiencies and Tuberculosis Susceptibility

Micronutrient deficiencies contribute to weakening the immune function and increasing TB susceptibility by impairing both innate and adaptive immune responses essential for controlling M. tuberculosis. Vitamin D deficiency, in particular, is associated with impaired phagocyte activation and reduced M. tuberculosis killing, contributing to increased disease susceptibility and severity,(43,44) which are critical for effective immune defence against TB infection. Zinc deficiency disrupts T-cell balance and cytokine signalling, resulting in suboptimal immune responses to TB antigens.(45) Further, studies have also shown that zinc and selenium deficiencies were significantly associated with a higher risk of developing TB in HIV-infected individuals,(46) highlighting the role of micronutrients in maintaining immune competence in vulnerable populations.(30,38) Abnormal iron metabolism also plays a critical role, as excessive iron accumulation within phagocytes promotes oxidative stress and creates a favourable intracellular environment for M. tuberculosis persistence, while iron deficiency (anaemia) remains highly prevalent among TB patients.(15,47) Collectively, deficiencies in key micronutrients impair immune responses, reduce antimicrobial peptide synthesis, and weaken antioxidant defences, thereby intensifying susceptibility to M. tuberculosis infection and delaying immunological recovery during and after disease.(35,36,38) Further, the biological mechanism reveals that undernutrition increases TB susceptibility through impaired immune defences, whereas active TB accelerates cachexia by increasing metabolic demands, suppressing appetite, and inducing oxidative stress.(22,34,37) This bidirectional nature of TB and undernutrition forms a double burden and influences the clinical or treatment outcomes (Figure 5).

Figure 5: Conceptual Framework and Bidirectional Interaction of TB and Undernutrition in India

Clinical Consequences of the Double Burden of Tuberculosis and Undernutrition

The double burden of TB and undernutrition creates a vicious cycle, where undernutrition drives TB incidence and severity, and TB increases the magnitude of undernutrition and higher nutritional demand in India. Further, poor nutritional status or severe undernutrition among TB patients leads to more serious and adverse clinical outcomes. These patients with a poor nutritional intake had significantly  higher risks of mortality, treatment failure, relapse, and drug resistance as compared to those with an adequate intake.(15,23) Moreover, the double burden of tuberculosis and undernutrition has been associated with substantially increased mortality, higher relapse rates, and poorer treatment outcomes. Evidence suggests that severe undernutrition at diagnosis may double the risk of death among TB patients and contribute to worse clinical outcomes.(15,16) Studies have reported that the nutritional status of TB patients was a prognostic indicator during treatment.(15,23) Insufficient weight gain or chronic energy deficiency (BMI<18.50 kg/m²) along with severe undernutrition during the first two months or initiation phase of anti-TB therapy were strongly associated with subsequent prolonged treatment, relapse, and mortality.(15,23,48) Moreover, the prevalence of severe undernutrition (BMI 16.0 to 17.0 kg/m²) at treatment initiation and the absence of body-weight gain during therapy have been significantly associated with an increased risk of unfavourable treatment outcomes and mortality.(23)The negative health effects observed in undernourished TB patients show how a lack of nutrition and problems with the immune system work together to make things worse. Inadequate intake of macronutrients and micronutrients compromises mucosal barrier integrity and cell-mediated immunity, increasing susceptibility to infection and limiting immune recovery.(15,38,47) Conversely, repeated or prolonged TB infection further exacerbates undernutrition by suppressing appetite, impairing nutrient absorption, increasing metabolic demands, and accelerating nutrient deterioration, thereby sustaining a vicious biological cycle of disease and nutritional decline.(15,34,44) Therefore, these research findings showed that undernutrition is not merely a coexisting condition but a central driver of poor TB treatment outcomes. Furthermore, year-wise spatial analysis of TB incidence showed substantial regional variation across India between 2018 and 2023, with a rise in TB cases (Figure 6). In this six-year time span, the northern region (e.g., Uttar Pradesh and Delhi) and the eastern region (e.g., Bihar and West Bengal) of India contributed the largest share of cases, from 0.60 to 1.44 million and 0.26 to 1.28 million, respectively. A marked decline was also observed in all regions during COVID-19 (2020), followed by an increase in incidence by 2022, particularly in the northern and eastern regions. Most regions stabilised in diagnosing and monitoring TB cases by 2023, indicating a recovery in TB surveillance and reporting systems (Figure 6).

Figure 6: State-wise overall tuberculosis burden in India (2018-2023) (India TB Report 2019-2024)

Effect of Nutritional Supplementation in Tuberculosis

Nutritional supplementation plays a crucial role in TB management, particularly among patients with a high undernutrition burden, as undernutrition worsens the TB outcomes and increases mortality risks.(49,50)Initial cohort studies in India reported significant differences in sputum culture conversion, with several re-evaluations indicating that patients receiving nutritional supplementation experienced faster sputum conversion and higher rates of bacteriological cure.(23,50) Later intervention indicated that the nutritional supplementation among TB patients had resulted in a significant gain in body weight, mid-upper arm circumference, BMI, and muscle mass alongside reductions in adverse clinical outcomes and improved immune markers (e.g., haemoglobin and lymphocyte counts) over extended follow-up periods and successful treatment completion over time.(49,50) Further, an early weight gain was significantly associated with reduced TB-related mortality and improvements in the quality of life.(23,50) Moreover, supplementation with high-energy diets and micronutrients, such as zinc combined with vitamin A and vitamin D, has also been shown to improve nutritional indices, positive immunological outcomes, and recovery trajectories and reduce mortality in TB patients.(45,51) Evidence from intervention studies suggests that providing staple cereals, pulses, oils, and other calorie-dense foods to tuberculosis patients is associated with improved nutritional status, better treatment outcomes, and enhanced recovery during therapy.(49,50) A large study in India (i.e., RATIONS) reported that providing food rations and micronutrients to households contacting TB patients significantly reduced the TB incidences (e.g., 39.00-48.00%), thus highlighting the preventive potentials of nutritional supplementation.(49) Additionally, statistical modelling studies indicated that TB prevalence can be diminished sustainably by supplying rations of 750 kcal/day and multivitamins to household contacts, which is cost-effective for both the government and society.(52) The nutritional interventions are cost-effective in high TB burden settings like India, and the necessary inclusion of nutritional support in TB control programmes enhances individual treatment outcomes and alleviates food insecurity, enhances treatment completion, and reduces transmission, thereby strengthening TB elimination efforts in India.

Paediatric TB in the Context of Undernutrition

The prevalence of paediatric TB is often underestimated as a significant part of the TB burden and is closely associated with the burden of undernutrition, being a major risk factor, which has become a public health concern over the last decade in India. Undernourished children exhibit impaired immune functions that increase the susceptibility to M. tuberculosis infection and contribute to a more severe and progressive form of disease, especially in rural and socioeconomically vulnerable populations.(53,54) This vulnerability is most pronounced among children <5 years of age with severe acute malnutrition and close contact with infectious or drug-resistant TB cases, where TB progression is often rapid and diagnosis is challenging.(54,55) Despite this elevated risk over the last decade, approximately 13.00% of the national TB burden, only a small portion of paediatric TB cases, are currently detected, and the rest remain underdiagnosed in India.(9)TB incidence initially declined 22.00% (2012-2013), then rose gradually until 2016, spiking sharply from 2017 to a 2019 peak, reflecting an overall 38.00% rise, likely due to improved detection and reporting. The disruption in healthcare services caused by COVID-19 has significantly impacted TB detection in 2020. But there was a strong rebound after the pandemic, with cases steadily rising from 2021 to 2023. The figure was a 40.00% increase since 2020 and the highest level ever recorded in the series (Figure 7). Overall, the challenges with early screening and diagnostic tools, the low accuracy of traditional microbiological tests, and the difficulties in getting samples from children, especially in places with limited healthcare resources, contribute to the rising prevalence of cases and the ongoing connection between paediatric TB and undernutrition in India.(53) Thereby, the emerging evidence highlights that better healthcare accessibility, nutrition rehabilitation, and child healthcare centres may serve as important points for diagnosing TB among high-risk children, highlighting the close epidemiological and clinical association between undernutrition and paediatric TB burden in India.(55,56)

Figure 7: Paediatric TB cases over the last decade, according to the India TB report (2013-24)

Policy Landscape and Programmatic Response in India

India has increasingly recognised undernutrition as a critical determinant of TB outcomes and incorporated nutritional supports into its national TB control and eradication framework. According to the target of the SDGs to eradicate the TB epidemic by the year 2030, the National Strategic Plan of TB Elimination 2020-2025 of India focuses on early diagnosis, patient-centered care, nutritional support, and multisectoral action. The TB-undernutrition nexus operates in two directions, which highlights the importance of nutrition-sensitive interventions and sustained disparities in diagnosis threatening universal health coverage. Integrated implementation should therefore be used to address social determinants and achieve TB elimination in India by 2030. Nutritional interventions were associated with improved treatment outcomes among TB patients, including reduced mortality, enhanced weight gain and body composition, faster sputum conversion, and improved recovery during treatment.(15,50)In this context, the Government of India introduced the Nikshay Poshan Yojana (2018), providing direct benefit transfers of ₹500 per month to all notified TB patients and specifically ₹750 per month for nutritional support during treatment for a minimum duration of six months, with extended support for those with DR-TB.(24,24) This monetary benefit is primarily used by the TB patients to purchase nutritious food items such as fruits and milk, aligning with the nutritional support goals of the scheme.(57)

This financial assistance benefited more than 7.5 million TB patients and has been associated with improved dietary intake, reduced weight loss, better treatment adherence, and enhanced recovery.(57,58) However, implementation challenges persist, including lack of awareness about the purpose of the scheme and delays in benefit disbursement due to bank account-related issues and Aadhaar-related barriers; delays in payments that hinder optimal utilization, and the limited adequacy of financial support relative to household nutritional needs, particularly among migrant workers, socio-economically marginalised populations, or patients who have been treated in the private sector with HIV co-infection.(57–59) Recent studies have highlighted a gradual improvement in programme coverage and efficiency, as the average time to receive benefits has halved in the past five years.(25,57,58) Furthermore, the Pradhan Mantri TB Mukt Bharat Abhiyan is a flagship campaign launched by the Prime Minister of India, aiming to eliminate TB by 2025, five years ahead of the global SDG target. Key components of this flagship programme include decentralised initiatives like TB-Free Panchayats and cities that leverage technologies such as the Nikshay digital surveillance system, telemedicine, and direct benefit transfers to support patients and reduce stigma (Table 1). The campaign also promotes active case finding, private sector engagement, and nutritional support, alongside investments in research for new diagnostics, drugs, and vaccines, recognising the critical role of novel tools in achieving TB elimination.

Beyond TB-specific nutritional and financial supports the Government of India has implemented a wide range of nutrition-sensitive social protection programmes that indirectly influence TB vulnerability and recovery.(9) These include the Integrated Child Development Services programme, which provides supplementary nutrition and growth monitoring for children under 6 years old and for pregnant or lactating women; the PM POSHAN (i.e., Midday Meal) scheme, which offers cooked food for students; the Pradhan Mantri Matru Vandana Yojana, for maternal and infant nutrition; and the Pradhan Mantri Garib Kalyan Anna Yojana, expanded for guaranteed subsidised grain distribution, especially during COVID-19. National initiatives such as the National Food Security Act (NFSA, 2013), food fortification under the National Health Mission (MoHFW, 2020), Poshan Abhiyaan 2.0 (2021), and the “One Nation, One Ration Card” system contribute to nutritional security and indirectly to the TB elimination programme by combating the determinants of the double burden of undernutrition and TB at the population level. Moreover, at the subnational level, efforts were aligned with national policies to financially support and provide supplementation to meet the local needs of the patients, enhance the desired support system, and improve treatment outcomes and economic development.

Challenges Towards Tuberculosis Control and Eradication

Despite ongoing national efforts, TB control and elimination continue to face persistent and interlinked challenges in the biological, diagnostic, programmatic, and social domains in India.(11,24) Firstly, undernutrition contributes to more than half of the TB incidence in India, increases the vulnerability to infection, delays recovery, and increases the likelihood of relapse and mortality, thereby reinforcing a self-perpetuating cycle of disease and deprivation.(15,16,21,60) This situation requires the implementation of intervention policies for TB that address undernutrition. Secondly, a major challenge is the diagnostic gap for TB in India. Although rapid molecular diagnostics such as Xpert MTB/RIF and expanded chest radiography have improved case detection, their access is limited, especially uneven in low- or limited-healthcare settings such as rural and tribal areas.(11,24,30) Similarly, there is a noticeable shortage of trained healthcare workers and inadequate infrastructure to execute diagnosis and initiate treatment specifically for paediatric TB, ETB, and DR-TB.(4,56)

These issues have a direct negative impact on the achievement of the SDG objective of eliminating India's TB epidemic by 2030 (SDG 3.3) through ambitious targets such as the reduction of incidence (i.e., 80.00%) and related mortality (i.e., 90.00%) compared to 2015. Despite progress, a decline in TB incidence and death rate was found to be modest, with challenges including DR-TB and a high burden of people living with undernutrition and HIV.(12,61) The close association between undernutrition and TB identifies nutrition-sensitive disease control interventions to decrease the susceptibility to the disease, enhance treatment success rates, and decrease relapse.(12,61) Inconsistent diagnostic disparities, especially in rural and tribal areas, are indicative of gaps in universal health coverage and still hinder the TB diagnosis, especially for paediatric TB,ETB, and DR-TB. Adopting integrated nutritional supports, fair diagnostic coverage, strengthened health systems, and multi-sectoral intervention to address the social determinants of health will therefore be necessary to meet the TB elimination target by 2030, in alignment with the SDG framework. Moreover, failure to meet the SDG targets by 2030 is projected to cause overwhelming deaths and millions in economic losses and also significantly affect COVID-19-related disruption.(61-63)

Conclusion

The present Systematic review provides strong evidence that undernutrition functions both as a cause and consequence of TB, contributing a significant hindrance to improving the existing condition of the TB burden in India. By integrating biological, social, and programmatic evidence, this review demonstrates how chronic energy deficiency or any nutritional deprivation compromises immune functions, adversely influences the treatment response or outcomes, and increases the likelihood of relapse in TB patients. Evidence also suggested that nutritional interventions, such as food-based supports and micronutrient supplementation, are strongly associated with significant improvements in treatment adherence, recovery trajectories, and patient well-being, hence enhancing the overall quality of life. However, gaps still exist in providing timely nutritional supplements, financial support, intervention programmes, and longitudinal monitoring, including post-treatment follow-ups. The recommendations are to include regular nutrition checks and BMI tracking in the National Tuberculosis Elimination Programme (NTEP) and to provide food assistance beyond just cash transfers, especially for groups in greatest need, such as children under 5 years, tribal communities, individuals residing in rural areas, and those in the lower socio-economic group. Such monitoring is necessary to prevent the transmission of M. tuberculosis infections and to strengthen elimination efforts among high-risk populations in endemic regions. Regular nutritional assessments, counselling, and support for TB care are recommended to improve overall treatment efficacy and patient survival. Future research may investigate models of social determinants that influence TB incidence in diverse high-endemic regions. We recommend the establishment of cost-effective diagnostic and treatment centres, the role of public-private partnerships in TB elimination programmes. The necessary upgrading of the TB elimination policy should be done not only to eradicate TB but also to ensure public health resilience in India.

Funding

This research study received financial assistance in the form of a University Grants Commission Non-NET Fellowship from the Government of India.

Conflicts of interest

Authors declare that there are no conflicts of interest.

Data availability

Data supporting the results of this study shall, upon appropriate request, be available from the corresponding author.

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